Re: [edk2-devel] [PATCH v1 2/2] UefiCpuPkg/PiSmmCpuDxeSmm: Check BspIndex first before lock cmpxchg

["Wu, Jiaxin" <jiaxin.wu@intel.com>]

Yes, thanks Mike, I will update the patch.



> -----Original Message-----
> From: Kinney, Michael D <michael.d.kinney@intel.com>
> Sent: Friday, February 2, 2024 2:21 AM
> To: devel@edk2.groups.io; Wu, Jiaxin <jiaxin.wu@intel.com>
> Cc: Ni, Ray <ray.ni@intel.com>; Laszlo Ersek <lersek@redhat.com>; Dong, Eric
> <eric.dong@intel.com>; Zeng, Star <star.zeng@intel.com>; Gerd Hoffmann
> <kraxel@redhat.com>; Kumar, Rahul R <rahul.r.kumar@intel.com>; Kinney,
> Michael D <michael.d.kinney@intel.com>
> Subject: RE: [edk2-devel] [PATCH v1 2/2] UefiCpuPkg/PiSmmCpuDxeSmm:
> Check BspIndex first before lock cmpxchg
> 
> 
> 
> > -----Original Message-----
> > From: devel@edk2.groups.io <devel@edk2.groups.io> On Behalf Of Wu,
> > Jiaxin
> > Sent: Thursday, February 1, 2024 3:20 AM
> > To: devel@edk2.groups.io
> > Cc: Ni, Ray <ray.ni@intel.com>; Laszlo Ersek <lersek@redhat.com>; Dong,
> > Eric <eric.dong@intel.com>; Zeng, Star <star.zeng@intel.com>; Gerd
> > Hoffmann <kraxel@redhat.com>; Kumar, Rahul R
> <rahul.r.kumar@intel.com>
> > Subject: [edk2-devel] [PATCH v1 2/2] UefiCpuPkg/PiSmmCpuDxeSmm:
> Check
> > BspIndex first before lock cmpxchg
> >
> > This patch is to check BspIndex first before lock cmpxchg operation.
> > It's the optimization to lower the resource contention caused by the
> > atomic compare exchange operation, so as to improve the SMI
> > performance for BSP election.
> >
> > Cc: Ray Ni <ray.ni@intel.com>
> > Cc: Laszlo Ersek <lersek@redhat.com>
> > Cc: Eric Dong <eric.dong@intel.com>
> > Cc: Zeng Star <star.zeng@intel.com>
> > Cc: Gerd Hoffmann <kraxel@redhat.com>
> > Cc: Rahul Kumar <rahul1.kumar@intel.com>
> > Signed-off-by: Jiaxin Wu <jiaxin.wu@intel.com>
> > ---
> >  UefiCpuPkg/PiSmmCpuDxeSmm/MpService.c | 12 +++++++-----
> >  1 file changed, 7 insertions(+), 5 deletions(-)
> >
> > diff --git a/UefiCpuPkg/PiSmmCpuDxeSmm/MpService.c
> > b/UefiCpuPkg/PiSmmCpuDxeSmm/MpService.c
> > index e988ce0542..479024d294 100644
> > --- a/UefiCpuPkg/PiSmmCpuDxeSmm/MpService.c
> > +++ b/UefiCpuPkg/PiSmmCpuDxeSmm/MpService.c
> > @@ -1652,15 +1652,17 @@ SmiRendezvous (
> >              }
> >            } else {
> >              //
> >              // Platform hook fails to determine, use default BSP
> > election method
> >              //
> > -            InterlockedCompareExchange32 (
> > -              (UINT32 *)&mSmmMpSyncData->BspIndex,
> > -              (UINT32)-1,
> > -              (UINT32)CpuIndex
> > -              );
> > +            if (mSmmMpSyncData->BspIndex == (UINT32)-1) {
> 
> If the field is UINT32, prefer to use MAX_UINT32 instead of typecase from
> signed to unsigned value.
> 
> > +              InterlockedCompareExchange32 (
> > +                (UINT32 *)&mSmmMpSyncData->BspIndex,
> > +                (UINT32)-1,
> 
> If the parameter is UINT32, prefer to use MAX_UINT32 instead of typecase
> from signed to unsigned value.
> 
> > +                (UINT32)CpuIndex
> > +                );
> > +            }
> >            }
> >          }
> >        }
> >
> >        //
> > --
> > 2.16.2.windows.1
> >
> >
> >
> > 
> >



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